Knee Fat Pad Impingement

Also known as Hoffa's syndrome or fat pad syndrome, the Infrapatellar fat pads (IFP) are two wedge-shaped fatty structures situated below the kneecap (patella), lying on either side of the patellar tendon (just underneath the knee cap). The fat pad’s function is to reduce load to the knee and protect the knee joint under normal physiological conditions. It is a dynamic structure that alters position, pressure, and volume throughout the knee during motion. It is flexible and able to change shape and volume to accommodate movement. When the fat pads become impinged, patients experience pain below the kneecap and along the sides of the patellar tendon.

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Causes of Knee Fat Pad Impingement

Impingement of the infrapatellar fat pads is typically associated with incorrect torsional movements, a direct blow, or a hyperextension injury of the lower limbs. The pat pad is normally mobile and moves out of the joint spaces of the knee normally as the knee bends and straightens. As the fat pad becomes inflamed and enlarged due to swelling, it is no longer able to move appropriately within the joint space during movement and over time can become pinched or impinged.

The anatomical location of the infrapatellar fat pad exposes it to mechanical load, especially when the leg is straight. If the fat pad becomes chronically inflamed due to repeated microtrauma, if not properly managed may lead to considerable tissue remodeling and the formation of scar tissue.

A person with knee hyperextension may be more prone to this condition. Predominantly seen in young women, jumping sports and ligamentous laxity are considered to be risk factors for infrapatellar fat pad impingement.

  • Incorrect Torsional Movements
  • Physical Trauma
  • Hyperextension Injury
  • Chronic Inflammation
  • Other Risk Factors

Symptoms of Knee Fat Pad Impingement

Fat pad impingement is often confused or connected to patellar tendonitis, which is the tendon that connects your patella (kneecap) to your tibia (shin bone). Patellar Tendonitis typically only causes pain to be underneath the patella at the location of the tendon. In contrast, fat pad impingement will cause pain on either side of the tendon, where the fat pads are located. Fat pad impingement is typically not associated with clicking, locking, or instability but is commonly associated with crepitus, a grinding or creaking sound that can be associated with joint movement.

Extending a bent knee will put pressure on the margins of the fat pads, and if inflamed, typically will elicit pain with infrapatellar fat pad impingement. In some cases, the kneecap may be tilted outward due to swelling underneath.

The pain is typically worse with jumping, prolonged standing, or any other position that causes the knees to hyperextend. Other specific activities that increase the load of the knee that may be painful with infrapatellar fat pad impingement include negotiating stairs, squatting, and running. Pain and discomfort with walking in flat shoes without adequate arch support can also exacerbate symptoms when fat pad impingement is present.

  • Pain on Either Side of Patellar Tendon
  • Grinding or Creaking Sound with Joint Movement
  • Pain When Extending a Bent Knee
  • Pain When Jumping or Standing for Prolonged Periods of Time

Diagnosis of Knee Fat Pad Impingement

MRI is the best imaging technique in diagnosing infrapatellar inflammation. However, it is recommended to refer the patient to MRI only to exclude any other pathology, particularly when there is a history of trauma.

Physical therapists are highly skilled in the evaluation and detecting the presence of infrapatellar fat pad impingement through various examination techniques. During the examination, the inflamed fat pad is often enlarged, firm in consistency, and easy to palpate.

Movement assessment to determine the presence of this condition involves taking the knee into passive and applied hyperextension by lifting the heel and applying anterior pressure on the tibia. This position typically will cause pain exclusively in the fat pad if it is inflamed. A movement assessment of the patella is important in detecting adhesions or movement restrictions during knee movement. This is done by gliding the patella in all four directions, looking for limited or painful movement.

Oftentimes, the condition is associated with tightness in the quadriceps and hip flexor muscles. Flexibility and strength testing of the hips, knees, and ankles is an important part of any thorough physical therapy examination.

Most importantly, physical therapists are experts in movement and will watch the patient complete various functional movements to include bending, walking, and squatting to identify faulty patterns which may be contributing to the irritation of the fat pad. As mentioned previously, flat feet and poor shoe wear can be strong contributors to fat pad impingement. A foot and shoe assessment is a vital part of any physical therapy evaluation.

Lastly, the examination should also aim to rule out any other radiating pathology from the spine and hip.

Treatment of Knee Fat Pad Impingement with Physical Therapy

Our physical therapists at Results Physiotherapy frequently treat patients with infrapatellar fat pad impingement. The length of time that a patient has been experiencing symptoms will dictate the length of time that it takes for symptoms to resolve. The first step in the recovery process is to modify or limit the positions and activities which might add to the pain and/or pressure on the pads. Your physical therapist will help to provide you with these specific recommendations with the identification of the provocative activities.

Manual Therapy

At Results, our therapists are highly trained in a manual therapy, hands-on approach. This includes:

  • Soft tissue treatment: Treatment of the muscles that are surrounding the fat pad which may be preventing or altering normal joint movement due to tightness or guarding.
  • Joint mobilization: Movement of the joints to improve or restore normal joint mobility. Joint mobilization will not only target the knee joint itself, but may also target other areas both above and below the knee which may be contributing to abnormal movement of your entire leg.

Strengthening

  • Targeted muscle training that is aimed at improving faulty movement patterns, proper muscle recruitment, and coordination.
  • Stabilization exercises that will target strength and endurance of the muscles which will help to support the knee thus improving hyperextension and other compensatory movements of the knee that are contributing to the pain.

Stretching

  • If tightness is identified during the examination, stretching of the hip flexor muscles and quadricep muscles might help to lessen some of the downward pressure that the patella may be applying to the fat pad.

Activity Training

  • Training that is targeted to your specific goals, recreational activities, and/or job requirements that will help to facilitate your return to your pre-injury functional status.

Taping

  • Taping may be helpful as a short-term strategy to reduce pressure or offload the fat pad, reducing the impingement. Though not a permanent solution, various taping techniques may help to provide short-term relief, allowing less pain during your daily activities.

Prevention Tips for Knee Fat Pad Impingement

In addition to seeking treatment for Knee Fat Pad Impingement, other recommendations that are frequently made to the patient experiencing symptoms of infrapatellar fat pad impingement include:

  • Avoiding flat foot shoe wear
  • Applying ice before and after activities over the affected area.
  • Anti-inflammatory medicines are also frequently used. In other circumstances, injections might be used to reduce or surgery to trim the fat pad are required. Rarely surgery is required to remove the inflamed portion of the fat pad.

Articles Related to Knee Fat Pad Impingement

References and Additional Research Reading

  1. Hannon J, Bardenett S, Singleton S, Garrison JC. Evaluation, Treatment, and Rehabilitation Implications of the Infrapatellar Fat Pad. Sports health. 2016;8(2):167-71.
  2. Duran S, Ak┼čahin E, Kocadal O, Aktekin CN, Hapa O, Genctürk ZB. Effects of body mass index, infrapatellar fat pad volume and age on patellar cartilage defect. Orthopaedic journal of sports medicine. 2014;2(11_suppl3):2325967114S00159.
  3. Genin J, Faour M, Ramkumar PN, Yakubek G, Khlopas A, Chughtai M et al. Infrapatellar Fat Pad Impingement: A Systematic Review. J Knee Surg. 2017;30(7):639-46.
  4. Dragoo JL, Johnson C, McConnell J. Evaluation and treatment of disorders of the infrapatellar fat pad. Sports medicine. 2012;42(1):51-67.
  5. Fat Pad Syndrome. (2021, February 4). Physiopedia, . Retrieved 02:56, March 19, 2021 from https://www.physio-pedia.com/index.php?title=Fat_Pad_Syndrome&oldid=266540.
 
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